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      <title>死信队列概念与处理 - 交互式测验</title>
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      </style>
    </head>
    <body>
      <div class="main-wrapper">
          <div class="quiz-container">
            <div class="quiz-header">
              <h1>死信队列概念与处理 - 交互式测验</h1>
              <p>检验你对文档内容的理解程度</p>
            </div>
            <div id="quiz-content">
                <div class="quiz-body">
                    <div class="progress-bar">
                        <div id="progress-indicator"></div>
                    </div>
                    <div id="question-container">
                      <p id="question-text"></p>
                      <ul class="options-list" id="options-list"></ul>
                    </div>
                    <div id="result-container"></div>
                    <div id="hint-container" class="hint-container"></div>
                </div>
                <div class="quiz-footer" id="quiz-footer">
                  <button id="prev-btn" class="nav-btn">上一题</button>
                  <button id="hint-btn" class="nav-btn" style="background-color: #ffc107; color: #333; box-shadow: 0 4px 12px rgba(255,193,7,0.3);">提示</button>
                  <button id="next-btn" class="nav-btn">下一题</button>
                </div>
            </div>
          </div>
      </div>

      <script>
        const quizData = [
  {
    "question": "在RocketMQ中，死信队列（DLQ）的核心功能是什么？",
    "options": [
      "用于存储因消费失败且重试多次后仍不成功的消息。",
      "用于备份所有被成功消费的消息，以供后续审计。",
      "作为消息的中转站，在系统高峰期临时缓存消息。",
      "用于归档所有过期的消息，以便进行大数据分析。"
    ],
    "correctAnswerIndex": 0,
    "explanation": "死信队列是专门用来处理那些无法被正常消费的消息的。当一条消息经过多次重试（例如，默认16次）后仍然处理失败，它就会被投递到死信队列中，这样做既能避免有问题的消息阻塞正常消费流程，也为后续的问题排查和人工干预提供了机会。",
    "source": "文档中「死信队列的概念和形成原因」部分",
    "hint": "文档开头对DLQ的定义是：“...用于存储无法被正常消费的消息。”"
  },
  {
    "question": "根据文档，以下哪项不是导致消息进入死信队列的直接原因？",
    "options": [
      "消息消费失败，并且重试次数超过了设定的最大值。",
      "生产者在发送消息时为消息指定了较低的优先级。",
      "设置了过期时间（TTL）的消息在过期前未被消费。",
      "消费者明确拒绝了某条消息，并设置了不重新入队的选项。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "文档中明确列举了导致消息进入死信队列的四个原因：消费失败超过最大重试次数、消息过期、消息被拒绝且不重新入队、队列达到最大长度。消息的优先级主要影响其被消费的顺序，与是否进入死信队列没有直接关系。",
    "source": "文档中「形成原因」部分",
    "hint": "请仔细回顾“形成原因”一节列出的四个具体条件，并思考哪个选项不在其中。"
  },
  {
    "question": "如果一个消费者组的名称是 `OrderProcessingGroup`，那么按照RocketMQ的命名规则，其对应的死信队列名称应该是什么？",
    "options": [
      "OrderProcessingGroup-DLQ",
      "DLQ_OrderProcessingGroup",
      "%DLQ%OrderProcessingGroup",
      "DEAD_QUEUE_OrderProcessingGroup"
    ],
    "correctAnswerIndex": 2,
    "explanation": "RocketMQ为死信队列设计了统一且明确的命名规范，其格式为 `%DLQ%+{原ConsumerGroup}`。因此，对于名为 `OrderProcessingGroup` 的消费者组，其死信队列名称就是 `%DLQ%OrderProcessingGroup`。",
    "source": "文档中「死信队列的命名规则」部分",
    "hint": "文档中给出了死信队列名称的固定前缀和与消费者组名的组合方式。"
  },
  {
    "question": "一旦消息进入死信队列，它的默认处理机制是什么？",
    "options": [
      "系统会自动以一个更长的延迟间隔进行重试。",
      "消息会立即被永久丢弃，以释放存储空间。",
      "系统不再进行自动重试，需要人工干预来处理。",
      "消息会在24小时后被自动重新发送到原始Topic。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "文档明确指出，进入死信队列的消息不会被系统自动重试。这是为了防止有问题的消息无限循环地消耗系统资源并持续失败。处理这些消息需要开发人员或运维人员介入分析，并采取手动恢复、消息转发等方式进行干预。",
    "source": "文档中「死信消息的重试机制」部分",
    "hint": "思考一下，对于一个持续失败的任务，系统应该继续自动尝试还是暂停并等待指令？"
  },
  {
    "question": "当一条消息被移入死信队列后，关于其属性的变化，以下描述哪项是正确的？",
    "options": [
      "仅保留消息体，所有原始属性（如Topic、消息ID）都会丢失。",
      "所有原始属性都会被保留，并且系统会为其添加一些额外的诊断属性，如重试次数。",
      "原始属性被一组全新的、与死信队列相关的属性所替换。",
      "为了节省空间，消息的所有属性都会被压缩并归档。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "死信消息的一个重要特性是它会保留原始消息的全部属性，这对于问题排查至关重要。同时，RocketMQ还会额外添加一些用于诊断的属性，例如失败原因、重试次数、最后一次消费失败的时间戳等，以提供更丰富的上下文信息。",
    "source": "文档中「死信消息的存储」部分",
    "hint": "为了方便排查问题，系统应该为死信消息保留和添加哪些信息？"
  },
  {
    "question": "根据文档中的“处理最佳实践”，当发现死信队列中有消息时，应当采取的首要步骤是什么？",
    "options": [
      "立即将所有死信消息重新发送到原始Topic进行重试。",
      "分析导致消息消费失败的根本原因。",
      "编写自动化脚本，将消息持久化到外部数据库。",
      "立即清空死信队列，以防止其积压过多影响性能。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "文档强调，处理死信消息的首要步骤是“根本原因分析”。盲目地重发消息很可能导致问题重现。只有先找出失败的原因（例如，业务逻辑错误、数据格式问题、下游服务不可用），才能采取正确的处理策略（如修复代码、修正数据），从而从根本上解决问题。",
    "source": "文档中「处理最佳实践」部分",
    "hint": "在解决任何技术问题时，我们通常推荐的第一步是什么？是直接动手还是先思考？"
  },
  {
    "question": "为了从源头上减少进入死信队列的消息数量，文档推荐了哪种预防性措施？",
    "options": [
      "在消费者端增加更详细的错误日志记录。",
      "无限制地增加消息的最大重试次数。",
      "在消息生产阶段增加数据格式和业务规则的检查。",
      "为消费者分配更多的系统资源，如内存和CPU。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "文档在最佳实践中提到了“增加消息前置检查”。这意味着在消息被发送（生产）出来之前，就对其进行校验，确保数据格式正确、符合业务规则。这种“左移”的质量保障思路可以有效阻止大量无效或错误的消息进入消息队列系统，从而从源头上减少死信消息的产生。",
    "source": "文档中「处理最佳实践」部分",
    "hint": "想一想，如何才能在问题发生之前就进行拦截？"
  }
];
        console.log("Quiz Data:", JSON.parse(JSON.stringify(quizData))); // 添加这行用于调试，以可展开的JSON格式输出
        
        let currentQuestionIndex = 0;
        let score = 0;
        // 存储每个问题的回答状态
        const userAnswers = new Array(quizData.length).fill(null); 

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        const optionsListEl = document.getElementById('options-list');
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        const quizContentEl = document.getElementById('quiz-content');
        const progressIndicatorEl = document.getElementById('progress-indicator');
        const prevBtn = document.getElementById('prev-btn');
        const nextBtn = document.getElementById('next-btn');
        const hintBtn = document.getElementById('hint-btn');
        const hintContainerEl = document.getElementById('hint-container');

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          optionsListEl.innerHTML = '';
          hintContainerEl.style.display = 'none'; // 隐藏提示
          
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            showFinalScore();
            return;
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            li.textContent = optionText;
            li.dataset.index = index; // Store index in a data attribute
            // 如果这道题已经回答过，恢复状态
            if (userAnswers[currentQuestionIndex] !== null) {
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                    li.classList.add('selected');
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          updateNavigationButtons();
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        function selectOption(optionIndex) {
            userAnswers[currentQuestionIndex] = optionIndex;
            const currentQuestion = quizData[currentQuestionIndex];
            const isCorrect = optionIndex === currentQuestion.correctAnswerIndex;

            // 重新计算分数
            score = userAnswers.reduce((acc, answer, index) => {
                return answer === quizData[index].correctAnswerIndex ? acc + 1 : acc;
            }, 0);

            showResult(isCorrect, currentQuestion);
            updateNavigationButtons();
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            const answeredQuestions = userAnswers.filter(answer => answer !== null).length;
            const progressPercentage = (answeredQuestions / quizData.length) * 100;
            progressIndicatorEl.style.width = `${progressPercentage}%`;
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            prevBtn.style.display = 'block';
            nextBtn.style.display = 'block';
            hintBtn.style.display = 'block'; // 显示提示按钮

            prevBtn.disabled = currentQuestionIndex === 0;
            nextBtn.disabled = false; // 最后一题时，下一题按钮不禁用，而是用于显示报告
            nextBtn.textContent = (currentQuestionIndex === quizData.length - 1) ? '查看报告' : '下一题';
            
            // 如果当前问题没有提示，则禁用提示按钮并隐藏提示内容
            if (!quizData[currentQuestionIndex].hint) {
                hintBtn.disabled = true;
                hintContainerEl.style.display = 'none';
                hintContainerEl.textContent = ''; // 清除旧的提示内容
            } else {
                hintBtn.disabled = false;
            }
        }

        function showResult(isCorrect, questionData) {
            resultContainerEl.innerHTML = ''; // 清空之前的结果
            const resultBox = document.createElement('div');
            resultBox.className = `result-box ${isCorrect ? 'correct' : 'incorrect'}`;
            
            let html = `<h3>${isCorrect ? '回答正确！' : '回答错误'}</h3>`;
            if (!isCorrect) {
                html += `<p><strong>正确答案是：</strong> ${questionData.options[questionData.correctAnswerIndex]}</p>`;
            }
            html += `<div class="explanation-text">${questionData.explanation}</div>`;
            html += `<div class="source-text">来源: ${questionData.source}</div>`;
            
            resultBox.innerHTML = html;
            resultContainerEl.appendChild(resultBox);

            // 禁用所有选项的点击事件，并高亮正确/错误答案
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                // 高亮正确答案
                if (index === questionData.correctAnswerIndex) {
                    child.classList.add('correct'); // 需要添加CSS样式
                    child.style.backgroundColor = '#d4edda';
                    child.style.borderColor = '#c3e6cb';
                }
                // 如果选错了，高亮错误选项
                if (!isCorrect && index === userAnswers[currentQuestionIndex]) {
                    child.classList.add('incorrect'); // 需要添加CSS样式
                    child.style.backgroundColor = '#f8d7da';
                    child.style.borderColor = '#f5c6cb';
                }
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        }

        function goToNextQuestion() {
            if (currentQuestionIndex < quizData.length - 1) {
                currentQuestionIndex++;
                loadQuestion();
            } else {
                showFinalScore();
            }
        }

        function goToPreviousQuestion() {
            if (currentQuestionIndex > 0) {
                currentQuestionIndex--;
                loadQuestion();
            }
        }
        
        function showHint() {
            const currentQuestion = quizData[currentQuestionIndex];
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                hintContainerEl.textContent = currentQuestion.hint;
                hintContainerEl.style.display = 'block';
            } else {
                hintContainerEl.style.display = 'none';
            }
        }

        function showFinalScore() {
            document.querySelector('.quiz-body').style.display = 'none';
            document.getElementById('quiz-footer').style.display = 'none';

            const correctCount = score;
            const totalQuestions = quizData.length;
            const answeredCount = userAnswers.filter(a => a !== null).length;
            const wrongCount = answeredCount - correctCount;
            const skippedCount = totalQuestions - answeredCount;
            const accuracy = totalQuestions > 0 ? Math.round((correctCount / totalQuestions) * 100) : 0;
            const errorRate = totalQuestions > 0 ? Math.round((wrongCount / totalQuestions) * 100) : 0;

            const finalScoreHtml =
                '<div class="final-score-container">' +
                '<h2>答题报告</h2>' +
                '<div class="score-summary">' +
                '<div class="score-card">' +
                '<h3>得分</h3>' +
                '<p>' + correctCount + ' / ' + totalQuestions + '</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>正确率</h3>' +
                '<p>' + accuracy + '%</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>错误率</h3>' +
                '<p>' + errorRate + '%</p>' +
                '</div>' +
                '<div class="score-card score-details">' +
                '<table>' +
                '<tr><td>正确</td><td>' + correctCount + '</td></tr>' +
                '<tr><td>错误</td><td>' + wrongCount + '</td></tr>' +
                '<tr><td>未答</td><td>' + skippedCount + '</td></tr>' +
                '</table>' +
                '</div>' +
                '</div>' +
                '<div class="report-actions">' +
                '<button id="review-btn">回顾测验</button>' +
                '<button class="primary" onclick="location.reload()">再试一次</button>' +
                '</div>' +
                '</div>';

            let reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }
            quizContentEl.insertAdjacentHTML('beforeend', finalScoreHtml);
            document.getElementById('review-btn').addEventListener('click', reviewQuiz);
        }

        function reviewQuiz() {
            const reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }

            document.querySelector('.quiz-body').style.display = 'block';
            document.getElementById('quiz-footer').style.display = 'flex';
            
            currentQuestionIndex = 0;
            loadQuestion();
            updateNavigationButtons(); // Ensure nav buttons are correctly displayed
        }

        // Event Delegation for options
        optionsListEl.addEventListener('click', (event) => {
            if (event.target && event.target.matches('li.option-item')) {
                // Check if the question has already been answered
                if (userAnswers[currentQuestionIndex] === null) {
                    const selectedIndex = parseInt(event.target.dataset.index, 10);
                    selectOption(selectedIndex);
                }
            }
        });

        prevBtn.addEventListener('click', goToPreviousQuestion);
        nextBtn.addEventListener('click', goToNextQuestion);
        hintBtn.addEventListener('click', showHint);
        
        // 初始加载
        loadQuestion();
      </script>
    </body>
    </html>
  